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The Synthesis and Structures of the Novel Pyridoxal Oxime Derivatives

Novel pyridoxal oxime derivatives were prepared and characterized by means of IR, H-1 and C-13 NMR spectroscopy. The crystal structures of the 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1, 2-dimethylpyridinium iodide 1 and 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1, 2-dimethylpyridinium chloride monohydrate 2 were determined by X-ray analysis. The both compounds crystallize in the triclinic crystal system, space group P (1) over bar. Crystal data: 1 a = 6.286(2) Angstrom, b = 8.748(4) Angstrom, c = 11.736(4) Angstrom, alpha = 104.02(3)degrees, beta = 94.70(3)degrees, gamma = 107.44(6)degrees, V = 589.0(4) Angstrom(3), Z = 2, R = 0.0526 ; 2 a = 6.8980(5) Angstrom, b = 8.6409(6) Angstrom, c = 11.1777(6) Angstrom, alpha = 111.138(5)degrees, beta = 93.114(6)degrees, gamma = 105.158(5)degrees, V = 591.57(7) Angstrom(3), Z = 2, R = 0.0492. The bond distances and angles in both structures agree very well. The main difference between these structures was observed in the orientation of the hydroxymethyl group with respect to the pyridinium ring. In the both structures intramolecular hydrogen bond forming six-membered ring were observed. The intermolecular O...I hydrogen bonds in the crystal structure of the compound 1 form dimers. In the crystal structure of compound 2, the water molecules and chlorines build eight-membered rings, which are also connected to pyridinium cations by O...Cl and O...O intermolecular hydrogen bonds forming a three-dimensional network.

quaternary pyridinium salts ; pyridoxal oxime derivatives ; X-ray structure analysis ; hydrogen bonds

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